Outhouse is not a bad idea, but a septic tank works better.
Get a section of PVC pipe, glue a cap on one end, fill it up, and glue a cap on the other. Put that in a larger length of iron pipe, and screw a cap on each end. Throw it in and fetch it back with a magnet.
This is commitment. No one, repeat, no one is going to look at the bottom of a septic tank. What you are talking about would be for 10s of thousands of $$s. Real commitment